My almost brother in law has had a few surgeries on his brain. Because he has a cyst that grows right in the centre of it. His only symptom was that he was constantly hungry. They only found it because he got in a car accident and they scanned his head to check for a concusssion or soemthing and found the baseball sized cyst.
He had to learn basic things again, like controlling his bodily functions. But was fine with all that within a few months. They have to keep re-treating it using a 'gamma knife' which I believe is a form of radiation now.
His only issues now are that he has slight double vision (therefore can't drive) and his short term memory, for example I met him right after the operation, so for about 5 years he didn't recognize me but he remembers that his wife's little brother has a partner. He is starting to get better now though. The last two times I've seen him he recognized me, didn't know my name but recognized me. The brain creates new pathways to make up for what was damaged or lost eventually. It just takes time.
I also find his mind is selective, he will remember random things that happen after the operation very clearly. Like a meal on a certain date, that people are coming over but not who, birthdays but not who they belong to and he's also able to count down the days till he and his wife's first baby will be born next february!!
He's also one of the most positive, happiest people I know!
Don't lose hope and try not to worry about the worst thing possible, because it might not even happen, and then you worried for nothing!
I will pray for you and your husband and good luck to you both on Tuesday, be brave, both of you.